Crack stops, guard rings and other moisture oxidation barriers (MOB) are structures fabricated along the perimeter of an integrated circuit chip to prevent delamination of the various layers of the integrated circuit chip and other edge damage that may occur during “dicing” of individual integrated circuit chips. The guard rings and MOBs are sometimes referred to as crack stops. These structures can protect the active area of the chip from moisture, mobile ions, and mechanical damage. For example, the guard rings can prevent moisture from corroding the structures on the integrated circuit chip. Also, the guard rings can prevent damage to the components within an active area of the integrated circuit due to cracking that may form during the dicing process.
More specifically, after formation of the active and passive components, the wafer is cut or diced into individual integrated circuit chips, either by sawing or by scribing and breaking. During the cutting or dicing process, the wafer is subjected to high shear stresses which can cause cracks extending inwardly from the edges of each chip. Due to the stresses encountered when dicing the chip, or even later during use, cracks can propagate inward from the edges of the chip and eventually reach the active portion of the chip, damaging semiconductor devices disposed in the active region. Guard rings, though, can prevent the propagation of cracks from reaching the active region of the chip.
Guard rings, though, can be damaged due to dicing issues. Also, guard rings use valuable real estate on the integrated circuit.